Photoluminescence properties and energy transfer of SrZn2(PO4)2:Sn2+, Mn2+ phosphor

In this paper, SrZn2(PO4)2:Sn2+ (SZ2P:Sn2+), SrZn2(PO4)2:Mn2+ (SZ2P:Mn2+), SrZn2(PO4)2:Sn2+, and Mn2+ (SZ2P:Sn2+, Mn2+) phosphors are prepared by high temperature solid state reaction. The X-ray diffraction patterns and photoluminescence spectra of the phosphors are investigated in detail. The emission spectrum of SZ2P:Sn2+ is a wide band peaking at 461 nm due to 3P1 →1S0 transition of Sn2+, and overlaps effectively with the excitation spectrum of SZ2P:Mn2+, which shows that the absorption of SrZn2(PO4)2 host, and a series of peaks at 352, 373, 419, 431, and 466 nm, corresponding to 6A1(6S)→4E(4D), 6A1(6S)→4T2(4D), 6A1(6S)→[4A1(4G), 4E(4G)], 6A1(6S)→4T2(4G) and 6A1(6S) →4T1(4G) transition, respectively, are assigned to a wide band ranging from 200 nm to 300 nm. Therefore, luminescence intensity of Mn2+ is enhanced significantly by co-doping Sn2+ in SrZn2(PO4)2 host. According to the Dexter's energy transfer formula of multipolar interaction and Reisfeld's approximation, it is demonstrated that the energy transfer between Sn2+ and Mn2+ is due to the quadripole-quadripole interaction of the resonance transfer. The critical distance (Rc) of energy transfer is calculated to be about 1.78 nm. The tunable color is achieved by changing the doping concentrations of Sn2+ and Mn2+. The SZ2P:Sn2+, Mn2+ phosphor could emit strong blue-white light under the excitation of 254 nm ultraviolet (UV) light. The result shows that the SZ2P:Sn2+, Mn2+ is a promising phosphor for compact fluorescent lamp, and with the development of short wave UV semiconductor chip, this phosphor has potential applications in white light emitting diodes in the near future.